Our recent studies have shown that metaphase durations are prolonged in many tumor and transformed cells. This increase is unrelated to chromosome number and can account in part for the increased mitotic indices and metaphase/prophase ratios reported for some tumors. Since calcium ions play important roles in cell division, we intend to utilize fluorescent probes and computerized quantitative video intensification microscopy (QVIM) to: (1)\determine whether differences exist in membrane-associated or free cytosolic calcium levels in various normal and transformed cells and whether such differences correlate with alterations in metaphase durations; (2)\determine the effects of agents which alter intracellular pools on membrane-associated and free calcium and on metaphase durations in each cell type; (3)\determine whether increases in metaphase durations and alterations in calcium pools in transformed cells are related to certain changes in mitochondria; and (4)\begin studies of the levels of membrane-associated and free cytosolic calcium levels during the course of the mitotic cycle and determine how these may differ between normal and neoplastic cells.